Multidimensional Vectors

[adbharad]

m trying to get data to store in multidimensional vectors. While executing m getting Error : "vector subscript out of range".
I think the way i am trying to store the values in the vector is causing the issue.

using namespace std;

int main()
{
char n1[30];
string noun,line,con;
size_t pos, len,i,j;
vector <vector <string> > c;

ifstream datafile;
datafile.open("COOCS.txt");

if (datafile.is_open())
{
for (i = 0; i <= 6; i++)
{
cout << "enter the Noun:";
cin.getline(n1, sizeof(n1));
string n1_1(n1);


while (noun != n1_1)
{
getline(datafile, line);
size_t length = line.size();
size_t start = line.find('\t');
noun = line.substr(pos = 0, len = start);
c[i].push_back(noun);
size_t n_len = noun.size();
line = line.substr(pos = n_len + 1, len = length);
}

size_t start1 = line.find('\t');

while (line != "/0")
{
con = line.substr(pos = 0, len = start1);
c1.push_back(con);
size_t con_len = con.find('-#-');
con = con.substr(pos = 0, len = con_len);

for (j = 0 ; ; j++)
{
c[j].push_back(con);
}
line = line.substr(start1 + 1);
}

datafile.clear();
datafile.seekg(0, ios::beg);
}
}


return 0;
}

[edge6768]

There is no conditional in your for-loop so it will never end and j will go past the end of the vector.

for (j = 0 ; /* Check if j is a valid subscript */  ; j++)
{
c[j].push_back(con);
}

You could use vector.size() function to get the number of elements currently in the vector, or keep track of how many you add independently.

[adbharad]

The problem is execution is not even reaching there, it gives error in the line

c[i].push_back(noun);



its the first value i am trying to insert into the vector

[JayhawkZombie]

Well, what's the length of the c vector when you try to do that?

c may have a length of 0, so c[0] doesn't contain a string vector yet, so it's out of bounds. You need to push a vector into c[0] (or c[i] for that matter) before you push strings into that inner vector.

[adbharad]

i guess what you are saying makes sense but can please help how to push a vector at the initial location.

[JayhawkZombie]

Here's an example

#include <string>
#include <vector>
#include <iostream>


int main()
{
  std::vector<std::vector<std::string>> D2Vector;
  
  std::vector<std::string> innerVector;
  innerVector.push_back("Some String");
  innerVector.push_back("Some OtherString");
  
  D2Vector.push_back(innerVector);
  
  std::vector<std::string> otherVector;
  otherVector.push_back("1st String in otherVector");
  
  D2Vector.push_back(otherVector);
  
  for (auto & vec : D2Vector)
  {
      std::cout << "Beginning to print vector" << std::endl;
      for (auto & str : vec)
      {
          std::cout << '\t' << str << std::endl;
      }
  }
    
 return 0;   
}

Produces:

Beginning to print vector
	Some String
	Some OtherString
Beginning to print vector
	1st String in otherVector

[adbharad]

That works. Thanks!!